ITPEC FE Morning October 2020 Question 20
Which of the following is an appropriate description of DRAM?
Explanation
Memory that needs refreshing, used as a PC's main memory — DRAM stores each bit as charge in a capacitor, which leaks and must be rewritten periodically.
One transistor and one capacitor per bit make DRAM dense and cheap per bit, so it provides the gigabytes of main memory. It is volatile and slower than SRAM.
Answer (a)
Why not others:
- •(b) — non-volatile NAND or NOR memory used in SSDs is flash memory
- •(c) — non-volatile memory erased and rewritten byte by byte is EEPROM
- •(d) — cells built from flip-flops that need no refresh are SRAM, which is fast and used for cache memory
Key rule: DRAM (capacitor, needs refresh, main memory) versus SRAM (flip-flop, no refresh, cache); flash and EEPROM are the non-volatile ones.
Computer Component · AI-written, may contain errors
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